Various techniques have been researched and developed for reducing combustion heat during combustion in an internal combustion engine to reduce emissions of nitrogen oxides (NOx), hydrocarbons, and the like, and reducing a mixture ratio of air and fuel to improve fuel efficiency.
As a representative technique for reducing combustion heat and NOx emissions and improving fuel efficiency, an exhaust gas recirculation (EGR) system has been researched and developed.
The EGR system includes an EGR conduit for circulating EGR gas from an exhaust system to an intake system, an EGR cooler for cooling temperature of the EGR gas, and an EGR valve for regulating the flow of the EGR gas.
The disclosure of this section is to provide background of the invention. Applicant notes that this section may contain information available before this application. However, by providing this section, Applicant does not admit that any information contained in this section constitutes prior art.